The present invention relates to improvements in solenoid-actuated proportional-control valves, and, in one particular aspect, to a unique and advantageous electrically operated fluid valve of low-cost and uncomplicated construction which accurately controls high-volume flows with the aid of a frictionless suspension and a pressure-counterbalancing bellows cooperating with its movable valving member.
Fluid valves exist in a wide variety of forms and sizes, serving a multitude of purposes, handling flowable materials whose characters range from light gaseous to heavy slurries and near-solids, and operable at various speeds under controls as diverse as simple binary (ON-OFF), proportional, direct-manual and remote-electrical. Those which would be capable of responding quickly to govern even relatively large flows with precision, and with expenditure of little electrical power, are of special interest in certain industrial processing, such as the flowmeter-controlled automatic regulation of flows of gases in semiconductor and integrated-circuit manufacture, and the improvements disclosed here are aimed at satisfying the demanding requirements which attend such uses. One of the serious problems commonly encountered has to do with disturbing effects of line pressures, which can have undue adverse influences on behavior of a valving member at or near closure; others have to do with friction, and with the large control forces which must be developed if broad-area flow passages are to be valved in accommodation of high rates and volumes of flow.
It has been recognized that pressure in the flow lines being controlled may be exploited to develop forces in aid of valving there, and that has resulted in classes of multi-stage valves in which, for example, a readily-actuated sensitive pilot stage is used, in turn, to regulate applications of the line pressures to a larger main valve in a bootstrapping manner which effectively amplifies the control to the pilot. Also, it has of course been well understood that products of pressures times areas acting on various surfaces represent forces whose magnitudes and directions can be employed usefully either to produce or resist displacements of movable members. As will be found from what is described here, a highly beneficial counterbalancing of certain normally-disturbing imbalances produced by fluid pressure differentials is consonant with related principles.